Fixing broken WiFi on a 2017 MacBook Pro
Using AltStore on my Mac broke WiFi
In an ill-fated effort to downgrade my iPad 2 to iOS 6, I used AltStore on my MacBook Pro running Catalina 10.15.6. After giving up, I deleted AltStore.app from Applications (and disabled its frankly worrying Mail plugin). I noticed immediately afterward that my Mac would no-longer connect to the internet - iCloud began to complain and Safari wouldn't load web pages, although WiFi discovery was still working, and I was 'Connected with an IP Address' to my home WiFi. I could also connect to Personal Hotspot, but the internet didn't work over that either. It should be noted that Ethernet (through USB-C) still worked perfectly.
To fix this issue, Apple Support told me to reinstall macOS (which isn't as bad as it seems since you keep your files, etc.), but I wanted to hold off.
I actually fixed the issue by taking a Terminal to
/Library/Preferences/SystemConfiguration and, after backing up the whole
folder elsewhere, deleting the following files:
NetworkInterfaces-pre-upgrade-new-target.plist NetworkInterfaces-pre-upgrade-source.plist NetworkInterfaces.plist com.apple.airport.preferences.plist com.apple.wifi.message-tracer.plist preferences-pre-upgrade-new-target.plist preferences-pre-upgrade-source.plist preferences.plist
Note: Some of these were probably unnecessary, but didn't hurt.
After doing so, emptying the Bin and restarting, WiFi was working again!Back